<?php

namespace App\Http\Controllers;

use App\Models\Comment;
use App\Models\CommentLike;
use App\Models\Video;
use App\Notifications\NewCommentLikeNotification;
use App\Notifications\NewCommentNotification;
use App\Notifications\NewReplyNotification;
use App\Services\LlmLyricsService;
use App\Support\SafeNotifier;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;

class CommentController extends Controller
{
    public function __construct()
    {
        $this->middleware('auth')->except(['index', 'translate']);
    }

    public function index(Video $video)
    {
        $comments = $video->comments()->whereNull('parent_id')->with(['user', 'replies.user'])->get();

        return response()->json($comments);
    }

    public function store(Request $request, Video $video)
    {
        $request->validate([
            'body'      => 'required|string|max:1000',
            'parent_id' => 'nullable|exists:comments,id',
        ]);

        $commenter = Auth::user();

        // Idempotency guard: a client that retries (duplicate listeners after
        // an SPA swap, fast double-click, flaky connection) can POST the same
        // comment twice. We dedupe on two signals:
        //
        //   1. X-Idempotency-Key — the fetch() client sends a per-attempt
        //      UUID; the browser's own retry logic reuses the same value.
        //      This catches the deliberate-retry case before body comparison.
        //
        //   2. Identical (user, video, parent, body) within 60s — covers
        //      the duplicate-listener case where two independent fetch()es
        //      fire with different idempotency keys for the same user intent.
        //
        // Either match returns the first-written comment unchanged.
        $idemKey = (string) $request->header('X-Idempotency-Key', '');
        $cacheKey = $idemKey !== ''
            ? 'comment-idem:' . $commenter->id . ':' . $video->id . ':' . substr(hash('sha256', $idemKey), 0, 40)
            : null;

        if ($cacheKey) {
            $existingId = \Illuminate\Support\Facades\Cache::get($cacheKey);
            if ($existingId && $existing = Comment::find($existingId)) {
                return response()->json([
                    'success' => true,
                    'comment' => $existing->load('user:id,name,avatar'),
                ]);
            }
        }

        $existing = $video->comments()
            ->where('user_id', $commenter->id)
            ->where('body', $request->body)
            ->where(function ($q) use ($request) {
                $request->parent_id
                    ? $q->where('parent_id', $request->parent_id)
                    : $q->whereNull('parent_id');
            })
            ->where('created_at', '>=', now()->subSeconds(60))
            ->latest('id')
            ->first();

        if ($existing) {
            if ($cacheKey) {
                \Illuminate\Support\Facades\Cache::put($cacheKey, $existing->id, now()->addMinutes(5));
            }
            return response()->json([
                'success' => true,
                'comment' => $existing->load('user:id,name,avatar'),
            ]);
        }

        $comment = $video->comments()->create([
            'user_id'   => $commenter->id,
            'body'      => $request->body,
            'parent_id' => $request->parent_id,
        ]);

        if ($cacheKey) {
            \Illuminate\Support\Facades\Cache::put($cacheKey, $comment->id, now()->addMinutes(5));
        }

        $comment->load('user:id,name,avatar');

        // Fire notifications (never notify yourself)
        if ($request->parent_id) {
            // Reply — notify the parent comment's author
            $parent = Comment::find($request->parent_id);
            if ($parent && $parent->user_id !== $commenter->id) {
                SafeNotifier::send($parent->user, new NewReplyNotification($video, $comment, $commenter));
            }
        } else {
            // Top-level comment — notify the video owner
            if ($video->user_id !== $commenter->id) {
                SafeNotifier::send($video->user, new NewCommentNotification($video, $comment, $commenter));
            }
        }

        return response()->json([
            'success' => true,
            'comment' => $comment->load('user:id,name,avatar'),
        ]);
    }

    public function update(Request $request, Comment $comment)
    {
        if ($comment->user_id !== Auth::id()) {
            return response()->json(['error' => 'Unauthorized'], 403);
        }

        $request->validate([
            'body' => 'required|string|max:1000',
        ]);

        $comment->update(['body' => $request->body]);
        $comment->load('user:id,name,avatar');

        return response()->json($comment->load('user:id,name,avatar'));
    }

    public function destroy(Comment $comment)
    {
        if ($comment->user_id !== Auth::id()) {
            return response()->json(['error' => 'Unauthorized'], 403);
        }

        $comment->delete();

        return response()->json(['success' => true]);
    }

    public function translate(Request $request, Comment $comment, LlmLyricsService $llm)
    {
        if (! $llm->isEnabled()) {
            return response()->json(['error' => 'Translation is not configured'], 503);
        }

        $target = (string) $request->input('target', 'en');

        // Derive a source-language hint from the comment author's most-frequent
        // access country (video_views + profile_visits, falling back to their
        // nationality setting). Never trust the client for this — it's used
        // to disambiguate scripts the LLM might otherwise misidentify.
        $topCountries = \App\Models\User::topCountriesFor([$comment->user_id]);
        $sourceCountry = $topCountries[$comment->user_id] ?? null;
        $sourceLang    = \App\Data\CountryLanguages::primary($sourceCountry);

        $translated = $llm->translate((string) $comment->body, $target, $sourceLang);

        if ($translated === '') {
            return response()->json(['error' => 'Translation failed'], 502);
        }

        return response()->json([
            'success'       => true,
            'translated'    => $translated,
            'target'        => $target,
            'source_hint'   => $sourceLang,
            'author_country'=> $sourceCountry,
        ]);
    }

    public function like(Comment $comment)
    {
        $userId  = Auth::id();
        $existing = CommentLike::where('comment_id', $comment->id)
                                ->where('user_id', $userId)
                                ->first();

        if ($existing) {
            $existing->delete();
            $liked = false;
        } else {
            CommentLike::create(['comment_id' => $comment->id, 'user_id' => $userId]);
            $liked = true;

            // Notify the comment author (not self-likes)
            if ($comment->user_id !== $userId) {
                $video = $comment->video;
                if ($video) {
                    SafeNotifier::send(
                        $comment->user,
                        new NewCommentLikeNotification($video, $comment, Auth::user())
                    );
                }
            }
        }

        $count = CommentLike::where('comment_id', $comment->id)->count();

        return response()->json(['liked' => $liked, 'count' => $count]);
    }
}